The present invention relates generally to bladder nuclear matrix proteins, called “NMPs” here, and more specifically to novel nuclear matrix proteins of the bladder which are associated with cell-proliferative disorders.
The early diagnosis of bladder cancer is central to the effective treatment of the disease. Currently, there are no methods available to easily and specifically identify the presence of bladder cancer cells. The prevailing technique for diagnosis of bladder cancer is to identify bladder cancer cells by morphological examination of the cells by a pathologist. A cellular hallmark of the transformed phenotype is abnormal nuclear shape, the presence of multiple nucleoli and altered patterns of chromatin organization. Nuclear structural alterations are so prevalent in cancer cells that they are commonly used as a pathological marker of transformation for many types of cancer. Nuclear shape is determined in part by the nuclear matrix, the dynamic skeleton of the nucleus.
The nuclear matrix is the structural component of the nucleus that determines nuclear morphology, organizes the DNA in a three-dimensional fashion that is tissue specific, and has a central role in the regulation of a number of nuclear processes including the regulation of gene expression. The nuclear matrix has been demonstrated to play a central role in the regulation of important cellular processes such as DNA replication and transcription. Getzenberg, J. Cell Biochem. 55: 22-31 (1994). The nuclear matrix is the framework or scaffolding of the nucleus and consists of the peripheral laminas and pore complexes, an internal ribonucleic protein network, and residual nucleoli. Berezney et al., Biochem. Biophys. Res. Comm. 60: 1410-17 (1974). The nuclear matrix consists of approximately 10% of the nuclear proteins and is virtually devoid of lipids, DNA and histones. Fey et al., Critical Reviews in Eukaryotic Gene Expression 1: 127-44 (1991).
A majority of the known NMPs are common to all cell types and physiologic states. A number of laboratories have identified NMPs which may be unique to certain cell types or states. Mitogenic stimulation and the induction of differentiation have been demonstrated to alter the composition of nuclear matrix proteins and structure. The nuclear matrix contains a number of associated proteins that have been demonstrated to be involved in transformation. Berezney first showed that the nuclear matrix is altered in transformation, examining hepatoma nuclear matrix proteins. Berezney et al., Cancer Res. 39: 3031-39 (1979). Fey and Penman demonstrated that tumor promoters induce a specific morphologic signature in the nuclear matrix-intermediate filament scaffold of kidney cells. Fey et al., Proc. Nat'l Acad. Sci. USA 81: 859-66 (1984). Fey and Penman went on to demonstrate that the pattern of NMPs differed between normal and tumorigenic cell lines. Fey et al., loc. cit. 85: 121-25 (1989). Recently, an antibody to a nuclear matrix protein, termed NM-200.4, was raised from the breast carcinoma cell line T-47D. Weidner et al., Am. J. Path. 138: 1293-98 (1991). This antibody reacts strongly with human breast carcinoma specimens as well as specimens from lung, thyroid, and ovarian cancers, but does not react with normal epithelial cells of similar origin, raising the possibility of the use of certain anti-NMP antibodies as diagnostic tools.
In co-pending application Ser. No. 08/015,624, the entire contents of which are incorporated by reference herein, it has been demonstrated when human prostate samples were examined, nuclear matrix proteins were identified that (1) were present only in the normal prostate and were missing in both prostate cancer and benign prostatic hyperplasia (BPH) (normal pattern), (2) were found only in the prostate cancer cells and missing in the normal prostate and BPH (prostate cancer pattern), and (3) were found in both normal and BPH samples but were absent from prostate cancers.
No nuclear matrix proteins have been identified heretofore, however, that are linked specifically to bladder cancer.
Currently, the only available method for bladder cancer detection is morphological examination of cytology samples or cystoscopic biopsies. This method is accurate for high grade lesions; however, a significant proportion of bladder tumors (25-45%) are low grade or well differentiated and escape detection upon cytologic examination of exfoliated cells. Cytologic examination is unable to detect low numbers of tumor cells and is unable to separate low grade or well differentiated cells from their normal counterparts. The diagnostic accuracy of cytology alone for the detection of low grade transitional carcinoma is between 49 and 64 percent. Repeating the study can increase the accuracy of cytology; however, this is a costly and time consuming practice for both the patient and physician. When bladder cancer is detected early at a localized stage, the five year survival rate is 94%. Disease that has spread regionally or distantly lowers survival to 49% and 6% respectively. Development of a sensitive screening assay that could specifically detect bladder carcinoma would significantly facilitate patient management and allow the earlier treatment of this disease.